U.S. Pat. No. 3,505,714 issued in 1967 to G. Boileau discloses the prior art relating to clipping or crimping metallic structural elements to each other. The Boileau patent shows clipping pliers having a pair of handles connected to one another and to a pair of jaws for clipping two metallic sheet elements to each other. One jaw is provided with a punch element having a pointed tip, and the other jaw is provided with an anvil portion. FIG. 2 of this patent shows the use of this tool, wherein two parallel and adjacent sheet elements are to be clipped. The anvil portion of the tool rests on one side of the pair of metallic sheet elements, and the punch is destined to engage the other side thereof, with the pointed tip piercing the two sheet elements and integrally linking one to the other thereby due to a pair of inter-nesting outturned lips formed in the sheet elements by said punch.
The invention disclosed in the Boileau patent is used to fixedly attach a number of vertical studs to a floor sill plate and a ceiling plate, for erecting a wall structure. This is accomplished by clipping each wall stud twice to the sill plate and twice to the ceiling plate. Indeed, the sill plate, ceiling plate and stud are usually channel-sectioned, i.e. with a main web and two edgewise longitudinal perpendicular side walls, thus forming a U-shaped cross-section. For erecting a wall structure, a number of structural studs are vertically positioned between the horizontal floor sill and the horizontal ceiling plate, with each channel-shaped stud engaging the interior channel of both the sill plate and the ceiling plate so that their side walls be parallel and adjacent at both extremities of the stud. Clipping of the stud to the ceiling plate is then accomplished, usually on both pairs of stud and ceiling plate adjacent walls. The same is accomplished for attaching the stud to the sill plate.
This requires that the work person handling the Boileau clipping tool clip four times the metallic sheets for each stud. Moreover, for reaching the ceiling plate, the work person will most likely need to use a scaffold or a self-standing ladder, which increases the complexity of the clipping operation, and the likelihood of the work person wounding himself by accidentally falling off his scaffold or ladder.
Another disadvantage of the Boileau patent is that the plier clipping tool shown therein does not reach very far inside the side walls of the channel-shaped studs and sill and ceiling plates: consequently, the clipping of the stud to the floor sill or of the stud to the ceiling plate, will often be very close to the edge of their side walls, which results in a less reliable attachment. The clipping must indeed be accomplished closer to the web of the channel-shaped stud and plate walls. Also, when trying to reach further away from the side edges of the stud and plate walls, the work person may try to clip the metallic sheets by twisting the pliers into an inefficient angle to obtain a better clipping position: this is also undesirable.
In Canadian patent application No. 2,072,762 published on Dec. 30, 1993 by the present applicant, there is disclosed an upright column equipped with a set of wheels and a crimping head unit at both its upper and its lower extremities. The column is destined to be inserted between a lower sill plate, fixedly attached to the floor, and an upper plate, fixedly attached to the ceiling. The column wheels rotatably engage the upper and sill plates to allow movement of the column therealong. The crimping head units installed at each extremity of the vertical column are not detailed in this Canadian application, except that it is stated that their purpose is to fixedly attach vertical studs onto the sill and upper plates. The studs, sill plate and upper plate are made of a metallic material.